5ej6

Publication Abstract from PubMed

Enamine is a well-known reactive intermediate mediating essential thiamine-dependent catalysis in central metabolic pathways. How-ever, this intermediate is not found in the thiamine-dependent catal-ysis of the vitamin K biosynthetic enzyme MenD. Instead, an active tetrahedral post-decarboxylation intermediate is stably formed in the enzyme and structurally determined at 1.34 A resolution in crystal. This intermediate takes a unique conformation that allows only one proton between its tetrahedral reaction center and the exo-ring ni-trogen atom of the aminopyrimidine moiety in the cofactor with a short distance of 3.0 A. It is readily convertible to the final product of the enzymic reaction with a solvent-exchangeable proton at its reaction center. These results show that the thiamine-dependent enzyme utilizes a tetrahedral intermediate in a mechanism distinct from the enamine catalytic chemistry.

A thiamine-dependent enzyme utilizes an active tetrahedral intermediate in vitamin K biosynthesis.,Song H, Dong C, Qin M, Chen Y, Sun Y, Liu J, Chan W, Guo Z J Am Chem Soc. 2016 May 23. PMID:27213829^[3]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.